Process for conversion of acyclic C5 compounds to cyclic C5 compounds and catalyst composition for use therein

ABSTRACT

Disclosed is a process for the conversion of acyclic C 5  feedstock to a product comprising cyclic C 5  compounds, such as for example, cyclopentadiene, and catalyst compositions for use in such process. The process comprising the steps of contacting said feedstock and, optionally, hydrogen under acyclic C 5  conversion conditions in the presence of a catalyst composition to form said product. The catalyst composition comprising a microporous crystalline ferrosilicate, a Group 10 metal, and, optionally, a Group 11 metal, in combination with an optional Group 1 alkali metal and/or an optional Group 2 alkaline earth metal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This invention claims priority to and the benefit of U.S. Ser. No.62/250,688, filed Nov. 4, 2015. This application relates to U.S. Ser.No. 62/250,675, filed Nov. 4, 2015, U.S. Ser. No. 62/250,681, filed Nov.4, 2015, and U.S. Ser. No. 62/250,689, filed Nov. 4, 2015.

FIELD OF THE INVENTION

This invention relates to a process for the conversion of acyclic C₅feedstock to a product comprising cyclic C₅ compounds, such as forexample, cyclopentadiene, and catalyst compositions for use in suchprocess.

BACKGROUND OF THE INVENTION

Cyclopentadiene (CPD) and its dimer dicyclopentadiene (DCPD) are highlydesired raw materials used throughout the chemical industry in a widerange of products such as polymeric materials, polyester resins,synthetic rubbers, solvents, fuels, fuel additives, etc. In addition,cyclopentane and cyclopentene are useful as solvents, and cyclopentenemay be used as a monomer to produce polymers and as a starting materialfor other high value chemicals.

Cyclopentadiene (CPD) is currently a minor byproduct of liquid fed steamcracking (for example, naphtha and heavier feed). As existing and newsteam cracking facilities shift to lighter feeds, less CPD is producedwhile demand for CPD is rising. High cost due to supply limitationsimpacts the potential end product use of CPD in polymers. More CPD-basedpolymer products and other high value products could be produced, ifadditional CPD could be produced, at unconstrained rates and preferablyat a cost lower than recovery from steam cracking. Cyclopentane andcyclopentene also have high value as solvents while cyclopentene may beused as a comonomer to produce polymers and as a starting material forother high value chemicals.

It would be advantageous to be able to produce cyclic C₅ compounds, suchas for example, CPD as the primary product from plentiful C₅ feedstockusing a catalyst system to produce CPD while minimizing production oflight (C⁴⁻) byproducts. While lower hydrogen content feedstock (forexample, cyclics, alkenes, dialkenes) may be preferred because thereaction endotherm is reduced and thermodynamic constraints onconversion are improved, non-saturates are more expensive than saturatefeedstock. Linear C₅ skeletal structure is preferred over branched C₅skeletal structures due to both reaction chemistry and the lower valueof linear C₅ relative to branched C₅ (due to octane differences). Anabundance of C₅ is available from unconventional gas and shale oil, aswell as reduced use in motor fuels due to stringent fuel regulations. C₅feedstock may also be derived from bio-feeds.

Dehydrogenation technologies are currently used to produce mono-olefinsand di-olefins from C₃ and C₄ alkanes, but not cyclic mono-olefins orcyclic di-olefins. A typical process uses Pt/Sn supported on alumina asthe active catalyst. Another useful process uses chromia on alumina.See, B. V. Vora, “Development of Dehydrogenation Catalysts andProcesses,” Topics in Catalysis, vol. 55, pp. 1297-1308, 2012; and J. C.Bricker, “Advanced Catalytic Dehydrogenation Technologies for Productionof Olefins,” Topics in Catalysis, vol. 55, pp. 1309-1314, 2012.

Still another common process uses Pt/Sn supported on Zn and/or Caaluminate to dehydrogenate propane. While these processes are successfulin dehydrogenating alkanes, they do not perform cyclization, which iscritical to producing CPD. Pt—Sn/alumina and Pt—Sn/aluminate catalystsexhibit moderate conversion of n-pentane, but such catalyst have poorselectivity and yield to cyclic C₅ products.

Pt supported on chlorided alumina catalysts are used to reform lowoctane naphtha to aromatics such as benzene and toluene. See, U.S. Pat.No. 3,953,368 (Sinfelt), “Polymetallic Cluster Compositions Useful asHydrocarbon Conversion Catalysts.” While these catalysts are effectivein dehydrogenating and cyclizing C₆ and higher alkanes to form C₆aromatic rings, they are less effective in converting acyclic C₅s tocyclic C₅s. These Pt on chlorided alumina catalysts exhibit low yieldsof cyclic C₅ and exhibit deactivation within the first two hours of timeon stream. Cyclization of C₆ and C₇ alkanes is aided by the formation ofan aromatic ring, which does not occur in C₅ cyclization. This effectmay be due in part to the much higher heat of formation for CPD, acyclic C₅, as compared to benzene, a cyclic C₆, and toluene, a cyclicC₇. This is also exhibited by Pt/Ir and Pt/Sn supported on chloridedalumina. Although these alumina catalysts perform both dehydrogenationand cyclization of C₆₊ species to form C₆ aromatic rings, a differentcatalyst will be needed to convert acyclic C₅ to cyclic C₅.

Ga-containing ZSM-5 catalysts are used in a process to produce aromaticsfrom light paraffins. A study by Kanazirev et al. showed n-pentane isreadily converted over Ga₂O₃/H-ZSM-5. See Kanazirev et al., “Conversionof C₅ aromatics and n-pentane over Ga₂O₃/H-ZSM-5 mechanically mixedcatalysts,” Catalysis Letters, vol. 9, pp. 35-42, 1991. No production ofcyclic C₅ was reported while upwards of 6 wt % aromatics were producedat 440° C. and 1.8 h⁻¹ WHSV. Mo/ZSM-5 catalysts have also been shown todehydrogenate and/or cyclize paraffins, especially methane. See, Y. Xu,S. Liu, X. Guo, L. Wang, and M. Xie, “Methane activation without usingoxidants over Mo/HZSM-5 zeolite catalysts,” Catalysis Letters, vol. 30,pp. 135-149, 1994. High conversion of n-pentane using Mo/ZSM-5 wasdemonstrated with no production of cyclic C₅ and high yield to crackingproducts. This shows that ZSM-5-based catalysts can convert paraffins toa C₆ ring, but not necessarily to produce a C₅ ring.

U.S. Pat. No. 5,254,787 (Dessau) introduced the NU-87 catalyst used inthe dehydrogenation of paraffins. This catalyst was shown todehydrogenate C₂₋₅ and C₆₊ to produce their unsaturated analogs. Adistinction between C₂₋₅ and C₆₊ alkanes was made explicit in thispatent: dehydrogenation of C₂₋₅ alkanes produced linear or branchedmono-olefins or di-olefins whereas dehydrogenation of C₆₊ alkanesyielded aromatics. U.S. Pat. No. 5,192,728 (Dessau) involves similarchemistry, but with a tin-containing crystalline microporous material.As with the NU-87 catalyst, C₅ dehydrogenation was only shown to producelinear or branched, mono-olefins or di-olefins and not CPD.

U.S. Pat. No. 5,284,986 (Dessau) introduced a dual-stage process for theproduction of cyclopentane and cyclopentene from n-pentane. An examplewas conducted wherein the first stage involved dehydrogenation anddehydrocyclization of n-pentane to a mix of paraffins, mono-olefins anddi-olefins, and naphthenes over a Pt/Sn-ZSM-5 catalyst. This mixture wasthen introduced to a second-stage reactor consisting of Pd/Sn-ZSM-5catalyst where dienes, especially CPD, were converted to olefins andsaturates. Cyclopentene was the desired product in this process, whereasCPD was an unwanted byproduct.

U.S. Pat. No. 2,438,398; U.S. Pat. No. 2,438,399; U.S. Pat. No.2,438,400; U.S. Pat. No. 2,438,401; U.S. Pat. No. 2,438,402; U.S. Pat.No. 2,438,403; and U.S. Pat. No. 2,438,404 (Kennedy) disclosedproduction of CPD from 1,3-pentadiene over various catalysts. Lowoperating pressures, low per pass conversion, and low selectivity makethis process undesirable. Additionally, 1,3-pentadiene is not a readilyavailable feedstock, unlike n-pentane. See also, Kennedy et al.,“Formation of Cyclopentadiene from 1,3-Pentadiene,” Industrial &Engineering Chemistry, vol. 42, pp. 547-552, 1950.

Fel'dblyum et al. in “Cyclization and dehydrocyclization of C₅hydrocarbons over platinum nanocatalysts and in the presence of hydrogensulfide,” Doklady Chemistry, vol. 424, pp. 27-30, 2009, reportedproduction of CPD from 1,3-pentadiene, n-pentene, and n-pentane. Yieldsto CPD were as high as 53%, 35%, and 21% for the conversion of1,3-pentadiene, n-pentene, and n-pentane respectively at 600° C. on 2%Pt/SiO₂. While initial production of CPD was observed, drastic catalystdeactivation within the first minutes of the reaction was observed.Experiments conducted on Pt-containing silica show moderate conversionof n-pentane over Pt—Sn/SiO₂, but with poor selectivity and yield tocyclic C₅ products. The use of H₂S as a 1,3-pentadiene cyclizationpromoter was presented by Fel'dblyum, infra, as well as in Marcinkowski,“Isomerization and Dehydrogenation of 1,3-Pentadiene,” M. S., Universityof Central Florida, 1977. Marcinkowski showed 80% conversion of1,3,-pentadiene with 80% selectivity to CPD with H₂S at 700° C. Hightemperature, limited feedstock, and potential of products containingsulfur that would later need scrubbing make this process undesirable.

López et al. in “n-Pentane Hydroisomerization on Pt Containing HZSM-5,HBEA and SAPO-11,” Catalysis Letters, vol. 122, pp. 267-273, 2008,studied reactions of n-pentane on Pt-containing zeolites includingH-ZSM-5. At intermediate temperatures (250-400° C.), they reportedefficient hydroisomerization of n-pentane on the Pt-zeolites with nodiscussion of cyclopentenes formation. It is desirable to avoid thisdeleterious chemistry as branched C₅ do not produce cyclic C₅ asefficiently as linear C₅, as discussed above.

Li et al. in “Catalytic dehydroisomerization of n-alkanes toisoalkenes,” Journal of Catalysis, vol. 255, pp. 134-137, 2008, alsostudied n-pentane dehydrogenation on Pt-containing zeolites in which Alhad been isomorphically substituted with Fe. These Pt/[Fe]ZSM-5catalysts were efficient dehydrogenating and isomerizing n-pentane, butunder the reaction conditions used, no cyclic C₅ were produced andundesirable skeletal isomerization occurred.

In view of this state of the art, there remains a need for a process toconvert acyclic C₅ feedstock to non-aromatic, cyclic C₅ hydrocarbon,particularly CPD, preferably at commercial rates and conditions.Further, there is a need for a catalytic process targeted for theproduction of cyclopentadiene which generates cyclopentadiene in highyield from plentiful C₅ feedstocks without excessive production of C⁴⁻cracked products and with acceptable catalyst aging properties. Thisinvention meets this and other needs.

SUMMARY OF THE INVENTION

In a first aspect, the invention relates to a process for conversion ofan acyclic C₅ feedstock to a product comprising cyclic C₅ compounds.This process comprising the steps of contacting said feedstock and,optionally, hydrogen under acyclic C₅ conversion conditions in thepresence of a catalyst composition of this invention to form saidproduct.

In a second aspect, the invention relates to a catalyst composition foruse in the acyclic C₅ conversion process. This catalyst compositioncomprising a microporous crystalline ferrosilicate comprising a Group 10metal, and, optionally, a Group 11 metal, in combination with anoptional Group 1 alkali metal and/or an optional Group 2 alkaline earthmetal. Useful microporous crystalline metallosilicate (includingmicroporous ferrosilicates) have framework types that may be selectedfrom the group consisting of MWW, MFI, LTL, MOR, BEA, TON, MTW, MTT,FER, MRE, MFS, MEL, DDR, EUO, and FAU.

The Group 10 metal is preferably, platinum, and more preferably in theamount of at least 0.005 wt %, based on the weight of the catalystcomposition. The Group 11 metal is preferably copper or silver. TheGroup 1 alkali metal is preferably sodium.

The microporous crystalline ferrosilicate has a SiO₂/Al₂O₃ molar ratiogreater than about 25, preferably in the range of from about 50 up toabout 1,000.

The microporous crystalline ferrosilicate has a Si/Fe molar ratiogreater than about 25, preferably in the range of from about 50 up toabout 1200.

The catalyst composition has an Alpha Value (as measured prior to theaddition of the Group 10 metal, preferably, platinum, and/or prior tothe addition of the optional Group 11 metal, preferably, copper orsilver) of less than about 25, or in the range of about 1 to about 25.

The Group 11 metal content of said catalyst composition is at least 0.01molar ratio to the Group 10 metal, based on the molar quantities of eachin the catalyst composition.

The molar ratio of said Group 1 alkali metal to Al is at least 1, and/orthe molar ratio of said Group 2 alkaline earth metal to Al is at least1.

The molar ratio of said Group 1 alkali metal to Al plus Fe is at least0.1, and/or the molar ratio of said Group 2 alkaline earth metal to Alplus Fe is at least 0.1.

The said catalyst composition provides at least one of (i) a conversionof at least about 40%, and/or (ii) a carbon selectivity tocyclopentadiene of at least about 30% of an n-pentane feedstock withequimolar H₂ under acyclic C₅ conversion conditions of a temperature inthe range of about 550° C. to about 600° C., an n-pentane partialpressure between 3 psia and 30 psia at the reactor inlet (21 to 207kPa-a), such as between 3 psia and 10 psia (21 to 69 kPa-a), and ann-pentane weight hourly space velocity between 5 and 20 hr⁻¹, such asbetween 10 and 20 hr⁻¹.

In a third aspect, the invention relates to a method of making thecatalyst composition. The method of making the catalyst compositioncomprising the steps of:

(a) providing a microporous crystalline ferrosilicate comprising a Group1 alkali metal and/or a Group 2 alkaline earth metal;

(b) heating said microporous crystalline ferrosilicate in one or moresteps to a first temperature of about 450° C. or above in an atmospherewhich comprises an inert gas;

(c) adding oxygen to said atmosphere until the oxygen concentration insaid atmosphere is up to about 20% and then cooling said microporouscrystalline ferrosilicate; and

(d) contacting said cooled microporous crystalline ferrosilicate of step(c) with a source of a Group 10 metal, and/or, optionally, a Group 11metal, to form said catalyst composition, whereby said catalystcomposition having said Group 10 metal and/or said Group 11 metaldeposited thereon. The amount deposited of said Group 10 metal is atleast 0.005 wt %, based on the weight of the catalyst composition.

In a fourth aspect, the invention relates to a catalyst composition madeby any one of the methods of this invention.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an X-ray diffraction (XRD) pattern of the as-synthesizedmaterial produced in Example 1.

FIG. 2 shows a scanning electron microscope (SEM) image of theas-synthesized material produced in Example 1.

FIGS. 3A and 3B show the yield of cyclic C₅ at varying temperaturesbefore and after hydrogen treatment resulting from the catalystcomposition performance evaluation of Example 2.

DETAILED DESCRIPTION OF THE INVENTION Definitions

For the purpose of this specification and appended claims, the followingterms are defined.

The term “saturates” includes, but is not limited to, alkanes andcycloalkanes.

The term “non-saturates” includes, but is not limited to, alkenes,dialkenes, alkynes, cyclo-alkenes and cyclo-dialkenes.

The term “cyclic C₅” or “cC₅” includes, but is not limited to,cyclopentane, cyclopentene, cyclopentadiene, and mixtures of two or morethereof. The term “cyclic C₅” or “cC₅” also includes alkylated analogsof any of the foregoing, e.g., methyl cyclopentane, methyl cyclopentene,and methyl cyclopentadiene. It should be recognized for purposes of theinvention that cyclopentadiene spontaneously dimerizes over time to formdicyclopentadiene via Diels-Alder condensation over a range ofconditions, including ambient temperature and pressure.

The term “acyclic” includes, but is not limited to, linear and branchedsaturates and non-saturates.

The term “aromatic” means a planar cyclic hydrocarbyl with conjugateddouble bonds, such as, for example, benzene. As used herein, the termaromatic encompasses compounds containing one or more aromatic rings,including, but not limited to, benzene, toluene and xylene, andpolynuclear aromatics (PNAs), which include, but are not limited to,naphthalene, anthracene, chrysene, and their alkylated versions. Theterm “C₆₊ aromatics” includes compounds based upon an aromatic ringhaving six or more ring atoms, including, but not limited to, benzene,toluene, and xylene and polynuclear aromatics (PNAs), which include, butare not limited to, naphthalene, anthracene, chrysene, and theiralkylated versions.

The term “BTX” includes, but is not limited to, a mixture of benzene,toluene, and xylene (ortho and/or meta and/or para).

The term “coke” includes, but is not limited to, a low hydrogen contenthydrocarbon that is adsorbed on the catalyst composition.

The term “C_(n)” means hydrocarbon(s) having n carbon atom(s) permolecule, wherein n is a positive integer.

The term “C_(n+)” means hydrocarbon(s) having at least n carbon atom(s)per molecule.

The term “C_(n−)” means hydrocarbon(s) having no more than n carbonatom(s) per molecule.

The term “hydrocarbon” means a class of compounds containing hydrogenbound to carbon, and encompasses (i) saturated hydrocarbon compounds,(ii) unsaturated hydrocarbon compounds, and (iii) mixtures ofhydrocarbon compounds (saturated and/or unsaturated), including mixturesof hydrocarbon compounds having different values of n.

The term “C₅ feedstock” includes a feedstock containing n-pentane, suchas, for example, a feedstock which is predominately normal pentane andisopentane (also referred to as methylbutane), with smaller fractions ofcyclopentane and neopentane (also referred to as 2,2-dimethylpropane).

All numbers and references to the Periodic Table of Elements are basedon the new notation as set out in Chemical and Engineering News, 63(5),27 (1985), unless otherwise specified.

The term “Group 10 metal” means an element in Group 10 of the PeriodicTable and includes, but is not limited to, nickel, palladium, andplatinum.

The term “Group 1 alkali metal” means an element in Group 1 of thePeriodic Table and includes, but is not limited to, lithium, sodium,potassium, rubidium, caesium, and a mixture of two or more thereof, andexcludes hydrogen.

The term “Group 2 alkaline earth metal” means an element in Group 2 ofthe Periodic Table and includes, but is not limited to, beryllium,magnesium, calcium, strontium, barium, and a mixture of two or morethereof.

The term “Group 11 metal” means an element in Group 11 of the PeriodicTable and includes, but is not limited to, copper, silver, gold, and amixture of two or more thereof.

The term “constraint index” is defined in U.S. Pat. No. 3,972,832 andU.S. Pat. No. 4,016,218, both of which are incorporated herein byreference.

As used herein, the term “molecular sieve of the MCM-22 family” (or“material of the MCM-22 family” or “MCM-22 family material” or “MCM-22family zeolite”) includes one or more of:

molecular sieves made from a common first degree crystalline buildingblock unit cell, which unit cell has the MWW framework topology. (A unitcell is a spatial arrangement of atoms, which if tiled inthree-dimensional space describes the crystal structure. Such crystalstructures are discussed in the “Atlas of Zeolite Framework Types,”Fifth edition, 2001, the entire content of which is incorporated asreference);

molecular sieves made from a common second degree building block, beinga 2-dimensional tiling of such MWW framework topology unit cells,forming a monolayer of one unit cell thickness, preferably one c-unitcell thickness;

molecular sieves made from common second degree building blocks, beinglayers of one or more than one unit cell thickness, wherein the layer ofmore than one unit cell thickness is made from stacking, packing, orbinding at least two monolayers of one unit cell thickness. The stackingof such second degree building blocks may be in a regular fashion, anirregular fashion, a random fashion, or any combination thereof and

molecular sieves made by any regular or random 2-dimensional or3-dimensional combination of unit cells having the MWW frameworktopology.

The MCM-22 family includes those molecular sieves having an X-raydiffraction pattern including d-spacing maxima at 12.4±0.25, 6.9±0.15,3.57±0.07, and 3.42±0.07 Angstrom. The X-ray diffraction data used tocharacterize the material are obtained by standard techniques using theK-alpha doublet of copper as incident radiation and a diffractometerequipped with a scintillation counter and associated computer as thecollection system.

As used herein, the term “molecular sieve” is used synonymously with theterm microporous crystalline material or “zeolite.”

As used herein, the term “carbon selectivity” means the moles of carbonin the respective cyclic C₅, CPD, C₁, and C₂₋₄ formed divided by totalmoles of carbon in the pentane converted. The term “carbon selectivityto cyclic C₅ of at least 30%” means that at least 30 moles of carbon inthe cyclic C₅ is formed per 100 moles of carbon in the pentaneconverted.

As used herein, the term “conversion” means the moles of carbon in theacyclic C₅ feedstock that is converted to a product. The term“conversion of at least 40% of said acyclic C₅ feedstock to a product”means that at least 40% of the moles of said acyclic C₅ feedstock wasconverted to a product.

As used herein, the term “ferrosilicate” means an iron-containingmicroporous crystalline structure that contains iron in the frameworkstructure and/or in the channel system.

As used herein, the term [Fe]-ZSM-5 means a ferrosilicate having a MFIframework structure type.

For the purpose of this invention, ferrosilicates and metallosilicatesare defined as microporous crystalline metallosilicates, such asmicroporous crystalline aluminosilicates, microporous crystallineferrosilicates, or other metal containing microporous crystallinesilicates (such as those where the metal or metal containing compound isdispersed within the crystalline silicate structure and may or may notbe a part of the crystalline framework. Microporous crystallinemetallosilicate (including microporous ferrosilicates) framework typesinclude, but are not limited to, or are selected from the groupconsisting of MWW, MFI, LTL, MOR, BEA, TON, MTW, MTT, FER, MRE, MFS,MEL, DDR, EUO, FAU, and a combination of two or more thereof. It isrecognized that the ferrosilicate may also contain small quantities ofother metallosilicates; most notably, aluminosilicates. The microporouscrystalline metallosilicates preferably have a constraint index of lessthan 12, alternately from 1 to 12, alternately from 3 to 12.

As used herein, the term “Alpha Value” is used as a measure of thecracking activity of a catalyst and is described in U.S. Pat. No.3,354,078 and in the Journal of Catalysis, vol. 4, p. 527 (1965); vol.6, p. 278 (1966) and vol. 61, p. 395 (1980), each incorporated herein byreference. The experimental conditions of the test used herein includeda constant temperature of 538° C. and a variable flow rate as describedin detail in the Journal of Catalysis, vol. 61, p. 395 (1980).

As used herein, the term “reactor” refers to any vessel(s) in which achemical reaction occurs. Reactor includes both distinct reactors, aswell as reaction zones within a single reactor apparatus and asapplicable, reactions zones across multiple reactors. For example, asingle reactor may have multiple reaction zones. Where the descriptionrefers to a first and second reactor, the person of ordinary skill inthe art will readily recognize such reference includes two reactors, aswell as a single reactor vessel having first and second reaction zones.Likewise, a first reactor effluent and a second reactor effluent will berecognized to include the effluent from the first reaction zone and thesecond reaction zone of a single reactor, respectively.

Feedstock

A cyclic C₅ feedstock useful herein is obtainable from crude oil ornatural gas condensate, and can include cracked C₅ (in various degreesof unsaturation: alkenes, dialkenes, alkynes) produced by refining andchemical processes, such as fluid catalytic cracking (FCC), reforming,hydrocracking, hydrotreating, coking, and steam cracking.

The acyclic C₅ feedstock useful in the process of this inventioncomprises pentane, pentene, pentadiene and mixtures of two or morethereof. Preferably, the acyclic C₅ feedstock comprises at least about50 wt %, or 60 wt %, or 75 wt %, or 90 wt % n-pentane, or in the rangefrom about 50 wt % to about 100 wt % n-pentane.

The acyclic C₅ feedstock, optionally, does not comprise C₆ aromaticcompounds, such as benzene, preferably C₆ aromatic compounds are presentat less than 5 wt %, preferably less than 1 wt %, preferably present atless than 0.01 wt %, preferably at 0 wt %.

The acyclic C₅ feedstock, optionally, does not comprise benzene,toluene, or xylene (ortho, meta or para), preferably the benzene,toluene, or xylene (ortho, meta or para) compounds are present at lessthan 5 wt %, preferably less than 1 wt %, preferably present at lessthan 0.01 wt %, preferably at 0 wt %.

The acyclic C₅ feedstock, optionally, does not comprise C₆₊ aromaticcompounds, preferably C₆₊ aromatic compounds are present at less than 5wt %, preferably less than 1 wt %, preferably present at less than 0.01wt %, preferably at 0 wt %.

The acyclic C₅ feedstock, optionally, does not comprise C⁴⁻ compounds,any C₄-compounds are present at less than 5 wt %, preferably less than 1wt %, preferably present at less than 0.01 wt %, preferably at 0 wt %.

Acyclic C₅ Conversion Process

The first aspect of the invention is a process for conversion of anacyclic C₅ feedstock to a product comprising cyclic C₅ compounds. Theprocess comprising the steps of contacting said feedstock and,optionally, hydrogen under acyclic C₅ conversion conditions in thepresence of any one of the catalyst compositions of this invention toform said product. The catalyst composition comprises a microporouscrystalline ferrosilicate, a Group 10 metal and/or, optionally, a Group11 metal, in combination with an optional Group 1 alkali metal and/or anoptional Group 2 alkaline earth metal. The catalyst composition may havea constraint index in the range of from about 1 to about 12.

The first aspect of the invention is also a process for conversion of anacyclic C₅ feedstock to a product comprising cyclic C₅ compounds, theprocess comprising the steps of contacting said feedstock and,optionally, hydrogen under acyclic C₅ conversion conditions in thepresence of any one of the catalyst compositions made by any one of themethods of this invention to form said product.

In the present invention, the acyclic C₅ hydrocarbon(s) contained in theC₅ feedstock is fed into a first reactor loaded with a catalyst, wherethe acyclic C₅ hydrocarbons contact the catalyst under conversionconditions, whereupon at least a portion of the acyclic C₅hydrocarbon(s) molecules are converted into CPD molecules, and areaction product containing CPD and, optionally, other cyclichydrocarbons (e.g., C₅ cyclic hydrocarbons such as cyclopentane andcyclopentene) exits the first reactor as a first reactor hydrocarboneffluent. Preferably, a hydrogen co-feedstock comprising hydrogen and,optionally, light hydrocarbons, such as C₁-C₄ hydrocarbons, is also fedinto the first reactor (as described in U.S. Ser. No. 62/250,702, filedNov. 4, 2015). Preferably, at least a portion of the hydrogenco-feedstock is admixed with the C₅ feedstock prior to being fed intothe first reactor. The presence of hydrogen in the feed mixture at theinlet location, where the feed first comes into contact with thecatalyst, prevents or reduces the formation of coke on the catalystparticles.

The product of the process for conversion of an acyclic C₅ feedstockcomprises cyclic C₅ compounds. The cyclic C₅ compounds comprise one ormore of cyclopentane, cyclopentene, cyclopentadiene, and includesmixtures thereof. The cyclic C₅ compounds comprise at least about 20 wt%, or 30 wt %, or 40 wt %, or 50 wt % cyclopentadiene, or in the rangeof from about 10 wt % to about 80 wt %, alternately from about 20 wt %to about 70 wt % of cyclopentadiene.

The acyclic C₅ conversion conditions include at least a temperature, apartial pressure, and a weight hourly space velocity (WHSV). Thetemperature is in the range of about 400° C. to about 700° C., or in therange from about 500° C. to about 650° C., preferably, in the range fromabout 500° C. to about 600° C.

The partial pressure is in the range of about 3 to about 100 psi (21 to689 kPa-a), or in the range from about 3 to about 50 psi (21 to 345kPa-a), preferably, in the range from about 3 to about 20 psi (21 to 138kPa-a). The weight hourly space velocity is in the range from about 1hr⁻¹ to about 50 hr⁻¹, or in the range from about 1 hr⁻¹ to about 20hr⁻¹. Such conditions include a molar ratio of the optional hydrogenco-feed to the acyclic C₅ hydrocarbon in the range of about 0 to 3(e.g., 0.01 to 3.0), or in the range from about 0.5 to about 2. Suchconditions may also include co-feeding C₁-C₄ hydrocarbons with theacyclic C₅ feed.

This invention relates to a process for conversion of n-pentane tocyclopentadiene comprising the steps of contacting n-pentane and,optionally, hydrogen (if present, typically H₂ is present at a ratio ton-pentane of 0.01 to 3.0) with any one of the catalyst compositions ofthis invention to form cyclopentadiene at a temperature of 450° C. to650° C., a partial pressure of 3 to about 100 psia, and a weight hourlyspace velocity of 1 hr⁻¹ to about 50 hr 1.

In any embodiment, this invention relates to a process for conversion ofn-pentane to cyclopentadiene comprising the steps of contactingn-pentane and, optionally, hydrogen (if present, typically H₂ is presentat a molar ratio of hydrogen to n-pentane of 0.01 to 3.0) with one ormore catalyst compositions, including but not limited to the catalystcompositions described herein, to form cyclopentadiene at a temperatureof 400° C. to 700° C., a partial pressure of 3 psia to about 100 psia atthe reactor inlet (21 to 689 kPa-a), and a weight hourly space velocityof 1 hr⁻¹ to about 50 hr⁻¹.

In the presence of the catalyst, a number of desired and undesirableside reactions may take place. The net effect of the reactions is theproduction of hydrogen and the increase of total volume (assumingconstant total pressure). One particularly desired overall reaction(i.e., intermediate reaction steps are not shown) is:n-pentane→CPD+3 Hz.

Additional overall reactions include, but are not limited to:n-pentane→1,3-pentadiene+2H₂,n-pentane→1-pentene+H₂,n-pentane→2-pentene+H₂,n-pentane→2-methyl-2-butene+H₂,n-pentane→cyclopentane+H₂,cyclopentane→cyclopentene+H₂, orcyclopentene→CPD+H₂.

Fluids inside the first reactor are essentially in gas phase. At theoutlet of the first reactor, a first reactor hydrocarbon effluent,preferably in gas phase, is obtained. The first reactor hydrocarboneffluent may comprise a mixture of the following hydrocarbons, amongothers: heavy components comprising more than 8 carbon atoms such asmultiple-ring aromatics; C₈, C₇, and C₆ hydrocarbons such as one-ringaromatics; CPD (the desired product); unreacted C₅ feedstock materialsuch as n-pentane; C₅ by-products such as pentenes (1-pentene,2-pentene, e.g.), pentadienes (1,3-pentadiene; 1,4-pentadiene, e.g.),cyclopentane, cyclopentene, 2-methylbutane, 2-methyl-1-butene,3-methyl-1-butene, 2-methyl-1,3-butadiene, 2,2-dimethylpropane, and thelike; C₄ by-products such as butane, 1-butene, 2-butene, 1,3-butadiene,2-methylpropane; 2-methyl-1-propene, and the like; C₃ by-products suchas propane, propene; and the like; C₂ by-products such as ethane andethene; methane; and hydrogen.

The first reactor hydrocarbon effluent may comprise CPD at aconcentration of C(CPD)1 wt %, based on the total weight of the C₅hydrocarbons in the first reactor hydrocarbon effluent; anda1≦C(CPD)1≦a2, where a1 and a2 can be, independently, 15, 16, 18, 20,22, 24, 25, 26, 28, 30, 32, 34, 35, 36, 38, 40, 45, 50, 55, 60, 65, 70,75, 80, or 85 as long as a1<a2.

The first reactor hydrocarbon effluent may comprise acyclic diolefins ata total concentration of C(ADO)1 wt %, based on the total weight of theC₅ hydrocarbons in the first reactor hydrocarbon effluent; andb1≦C(ADO)1≦b2, where b1 and b2 can be, independently, 20, 18, 16, 15,14, 12, 10, 8, 6, 5, 4, 3, 2, 1, or 0.5, as long as b1<b2. Preferably,0.5≦C(ADO)≦10.

As a result of the use of the catalyst and the choice of reactionconditions in the first reactor, a high CPD to acyclic diolefin molarratio in the first reactor hydrocarbon effluent can be achieved suchthat C(CPD)1/C(ADO)1≧1.5, preferably 1.6, 1.8, 2.0, 2.2, 2.4, 2.5, 2.6,2.8, 3.0, 3.2, 3.4, 3.5, 3.6, 3.8, 4.0, 5.0, 6.0, 8.0, 10, 12, 14, 15,16, 18, or 20. The high ratio of C(CPD)1/C(ADO)1 significantly reducesCPD loss as a result of Diels-Alder reactions between CPD and acyclicdienes in subsequent processing steps, and therefore, allows theprocesses of the present invention to achieve high DCPD yield and highDCPD purity for the subsequently produced DCPD fractions.

Desirably, the total absolute pressure and temperature of the firstreactor hydrocarbon effluent should be maintained at levels such thatthe dimerization of CPD to form DCPD is substantially avoided, and theDiels-Alder reactions between CPD and acyclic dienes are substantiallyinhibited.

Because the overall conversion from acyclic C₅ hydrocarbons to CPD andhydrogen results in substantial volume increase (assuming constant totalsystem pressure), a low partial pressure of CPD and/or a low partialpressure of hydrogen in the reaction mixture favors the conversion ofacyclic C₅ hydrocarbons. The total partial pressure of C₅ hydrocarbonsand hydrogen in the first reactor effluent at the outlet is desired tobe lower than atmospheric pressure. Thus, where insufficientco-feedstock of a C₁-C₄ hydrocarbon or other co-feedstock is introducedinto the first reactor, the total overall pressure of the first reactoreffluent is desirably sub-atmospheric, in order to achieve a level ofsatisfactory conversion from acyclic C₅ hydrocarbons to CPD. However,direct separation of a sub-atmospheric stream has the disadvantage ofpotential oxygen/air ingress into the system, resulting in oxidation ofCPD and other hydrocarbons and formation of undesirable species in thesystem. Thus, it is desirable that the first reactor hydrocarboneffluent is processed to a higher total pressure before separationthereof. Eductor systems can be used for that purpose (as described inU.S. Ser. No. 62/250,708, filed Nov. 4, 2015).

Catalyst Composition

The second aspect of the invention is a catalyst composition for theconversion of an acyclic C₅ feedstock and, optionally, hydrogen to aproduct comprising cyclic C₅ compounds, such as for example,cyclopentadiene. The catalyst composition comprises a microporouscrystalline ferrosilicate, a Group 10 metal, and/or, optionally, a Group11 metal, in combination with an optional Group 1 alkali metal and/or anoptional Group 2 alkaline earth metal. At least part of the Group 10metal and/or Group 11 metal can be part of the framework metal of theferrosilicate.

The microporous crystalline ferrosilicate has a SiO₂/Al₂O₃ molar ratiogreater than about 25, preferably in the range of from about 50 up toabout 1,000.

The microporous crystalline ferrosilicate has a Si/Fe molar ratiogreater than about 50, or greater than about 100, or greater than about500 or greater than about 1000, or greater than 1500, or in the rangefrom about 50 to about 1200, for from about 100 to about 500, or fromabout 50 to about 1000, or from about 50 to about 1500.

The Group 10 metal includes, or is selected from the group consistingof, nickel, palladium, and platinum, preferably platinum. The Group 10metal content of said catalyst composition is at least 0.005 wt %, basedon the weight of the catalyst composition. The Group 10 content is inthe range from about 0.005 wt % to about 10 wt %, or from about 0.005 wt% up to about 1.5 wt %, based on the weight of the catalyst composition.

The Group 1 alkali metal includes, or is selected from the groupconsisting of lithium, sodium, potassium, rubidium, cesium, and mixturesof two or more thereof, preferably sodium.

The Group 2 alkaline earth metal includes, or is selected from the groupconsisting of beryllium, magnesium, calcium, strontium, barium, andmixtures of two or more thereof.

The Group 11 metal is selected from the group consisting of copper,silver, gold, and mixtures of two or more thereof; preferably copper orsilver.

The Group 11 metal content of the catalyst composition is such that themolar ratio of Group 11 metal to Group 10 metal is at least 0.01, basedon the molar quantities of each in the catalyst composition. Preferably,the molar ratio of Group 11 metal to Group 10 metal is in the range fromabout 0.1 to 10 or from about 0.5 to 5 based on the molar quantities ofeach in the catalyst composition. The Group 11 metal may be added to thecatalyst composition during or after synthesis of the microporouscrystalline molecular sieve as any suitable Group 11 metal compound.

The catalyst composition has an Alpha Value (as measured prior to theaddition of the Group 10 metal, preferably platinum, and/or prior to theaddition of the optional Group 11 metal, preferably, copper or silver)of less than about 25, or in the range of from about 1 to about 25,preferably less than about 15.

The molar ratio of said Group 1 alkali metal to Al is at least 1, and/orthe molar ratio of said Group 2 alkaline earth metal to Al is at least1.

The molar ratio of said Group 1 alkali metal to Al plus Fe is at least0.1, such as greater than 1, and/or the molar ratio of said Group 2alkaline earth metal to Al plus Fe is at least 0.1, such as greater than1.

The metal may be present as an oxide. The Group 1 alkali metal oxide isa metal oxide of lithium, sodium, potassium, rubidium, cesium, andmixtures of two or more thereof. The Group 2 alkaline earth metal oxideis an oxide of beryllium, magnesium, calcium, strontium, barium, andmixtures of two or more thereof.

The Group 1 alkali metal and/or Group 2 alkaline earth metal may be asresidual from the crystallization process and/or added aftercrystallization.

The use of the catalyst compositions in the process of this inventionprovides a conversion of at least about 70%, or at least about 75%, orat least about 80%, or in the range from about 60% to about 80%, of saidacyclic C₅ feedstock under acyclic C₅ conversion conditions of ann-pentane containing feedstock with equimolar H₂, a temperature in therange of about 550° C. to about 600° C., an n-pentane partial pressurebetween 3 and 10 psia (21 to 69 kPa-a), and an n-pentane weight hourlyspace velocity between 10 and 20 hr⁻¹.

The use of any one of the catalyst compositions in the process of thisinvention provides a carbon selectivity to cyclic C₅ compounds of atleast about 30%, or at least about 40%, or at least about 50%, or in therange from about 30% to about 50%, under acyclic C₅ conversionconditions including an n-pentane feedstock with equimolar H₂, atemperature in the range of about 550° C. to about 600° C., an n-pentanepartial pressure between 3 psia and 30 psia at the reactor inlet (21 to207 kPa-a), such as between 3 psia and 10 psia (21 to 69 kPa-a), and ann-pentane weight hourly space velocity between 5 and 20 hr⁻¹, such asbetween 10 and 20 hr⁻¹.

The use of any one of the catalyst compositions in the process of thisinvention provides a carbon selectivity to cyclopentadiene of at leastabout 30%, or at least about 40%, or at least about 50%, or in the rangefrom about 30% to about 50%, under acyclic C₅ conversion conditionsincluding an n-pentane feedstock with equimolar H₂, a temperature in therange of about 550° C. to about 600° C., an n-pentane partial pressurebetween 3 psia and 30 psia at the reactor inlet (21 to 207 kPa-a), suchas between 3 psia and 10 psia (21 to 69 kPa-a), and an n-pentane weighthourly space velocity between 5 and 20 hr⁻¹, such as between 10 and 20hr⁻¹.

The catalyst compositions of this invention can be combined with amatrix or binder material to render them attrition resistant and moreresistant to the severity of the conditions to which they will beexposed during use in hydrocarbon conversion applications. The combinedcompositions can contain 1 to 99 wt % of the materials of the inventionbased on the combined weight of the matrix (binder) and material of theinvention. The relative proportions of microporous crystalline materialand matrix may vary widely, with the crystal content ranging from about1 to about 90 wt % and more usually, particularly when the composite isprepared in the form of beads, in the range of about 2 to about 80 wt %of the composite.

During the use of the catalyst compositions in the processes of thisinvention, coke may be deposited on the catalyst compositions, wherebysuch catalyst compositions lose a portion of its catalytic activity andbecome deactivated. The deactivated catalyst compositions may beregenerated by conventional techniques including high pressure hydrogentreatment and combustion of coke on the catalyst compositions with anoxygen-containing gas.

Method of Making the Catalyst Compositions

In the third aspect of the invention, the method of making the catalystcomposition comprising the steps of:

(a) providing a microporous crystalline ferrosilicate comprising a Group1 alkali metal and/or a Group 2 alkaline earth metal;

(b) optionally, heating said microporous crystalline ferrosilicate inone or more steps to a first temperature of at least about 450° C., or500° C., or 550° C. in an atmosphere which comprises an inert gas, suchas for example, helium, nitrogen, or an inert mixture of air andnitrogen, preferably nitrogen;(c) optionally, adding oxygen to said atmosphere until the oxygenconcentration in said atmosphere is up to about 10%, or about 20%, orabout 30% and then cooling said microporous crystalline ferrosilicate,preferably cooling to about ambient temperature, for example, about 25°C.; and(d) contacting said (optionally, cooled) microporous crystallineferrosilicate of step (a) or (c) with a source of a Group 10 metal,preferably platinum, to form said catalyst composition, whereby saidcatalyst composition having said Group 10 metal, and/or, optionally, aGroup 11 metal, deposited thereon.

The Group 10 metal may be added to the catalyst composition during orafter synthesis of the crystalline molecular sieve as any suitable Group10 metal compound.

One Group 10 metal is platinum, and a source of platinum includes, butis not limited to, one or more platinum salts, such as, for example,platinum nitrate, chloroplatinic acid, platinous chloride, platinumamine compounds, particularly, tetraamine platinum hydroxide, andmixtures of two or more thereof. Alternatively, a source of platinum isselected from the group consisting of chloroplatinic acid, platinouschloride, platinum amine compounds, particularly, tetraamine platinumhydroxide, and mixtures of two or more thereof.

The source of Group 11 metal is a source of copper or silver. The sourceof copper is selected from the group consisting of copper nitrate,copper nitrite, copper acetate, copper hydroxide, copperacetylacetonate, copper carbonate, copper lactate, copper sulfate,copper phosphate, copper chloride, and mixtures of two or more thereof.The source of silver is selected from the group consisting of silvernitrate, silver nitrite, silver acetate, silver hydroxide, silveracetylacetonate, silver carbonate, silver lactate, silver sulfate,silver phosphate, and mixtures of two or more thereof. When Group 10and/or Group 11 metals are added post-synthesis, they may be added byincipient wetness, spray application, solution exchange, and chemicalvapor disposition or by other means known in the art.

The amount deposited of said Group 10 metal is at least 0.005 wt %,based on the weight of the catalyst composition, or in the range from0.005 wt % to 10 wt %, based on the weight of the catalyst composition.

The Group 11 metal content of said catalyst composition is at least 0.01molar ratio to the Group 10 metal, based on the molar quantities of eachin the catalyst composition. In one or more embodiments, the Group 11molar ratio to Group 10 metal is in the range from about 0.1 to 10 orfrom about 0.5 to 5 based on the molar quantities of each in thecatalyst composition.

In the fourth aspect of the invention, the catalyst composition is madeby the method of this invention.

INDUSTRIAL APPLICABILITY

The first hydrocarbon reactor effluent obtained during the acyclic C₅conversion process containing cyclic, branched, and linear C₅hydrocarbons and, optionally, containing any combination of hydrogen, C₄and lighter byproducts, or C₆ and heavier byproducts is a valuableproduct in and of itself. Preferably, CPD and/or DCPD may be separatedfrom the reactor effluent to obtain purified product streams which areuseful in the production of a variety of high value products.

For example, a purified product stream containing 50 wt % or greater, orpreferably 60 wt % or greater of DCPD is useful for producinghydrocarbon resins, unsaturated polyester resins, and epoxy materials. Apurified product stream containing 80 wt % or greater, or preferably 90wt % or greater of CPD is useful for producing Diels-Alder reactionproducts formed in accordance with the following reaction Scheme (I):

where R is a heteroatom or substituted heteroatom, substituted orunsubstituted C₁-C₅₀ hydrocarbyl radical (often a hydrocarbyl radicalcontaining double bonds), an aromatic radical, or any combinationthereof. Preferably, substituted radicals or groups contain one or moreelements from Groups 13-17, preferably from Groups 15 or 16, morepreferably nitrogen, oxygen, or sulfur. In addition to the monoolefinDiels-Alder reaction product depicted in Scheme (I), a purified productstream containing 80 wt % or greater, or preferably 90 wt % or greaterof CPD can be used to form Diels-Alder reaction products of CPD with oneor more of the following: another CPD molecule, conjugated dienes,acetylenes, allenes, disubstituted olefins, trisubstituted olefins,cyclic olefins, and substituted versions of the foregoing. PreferredDiels-Alder reaction products include norbornene, ethylidene norbornene,substituted norbornenes (including oxygen containing norbornenes),norbornadienes, and tetracyclododecene, as illustrated in the followingstructures:

The foregoing Diels-Alder reaction products are useful for producingpolymers and copolymers of cyclic olefins copolymerized with olefinssuch as ethylene. The resulting cyclic olefin copolymer and cyclicolefin polymer products are useful in a variety of applications, e.g.,packaging film.

A purified product stream containing 99 wt % or greater of DCPD isuseful for producing DCPD polymers using, for example, ring openingmetathesis polymerization (ROMP) catalysts. The DCPD polymer productsare useful in forming articles, particularly molded parts, e.g., windturbine blades and automobile parts.

Additional components may also be separated from the reactor effluentand used in the formation of high value products. For example, separatedcyclopentene is useful for producing polycyclopentene, also known aspolypentenamer, as depicted in Scheme (II).

Separated cyclopentane is useful as a blowing agent and as a solvent.Linear and branched C₅ products are useful for conversion to higherolefins and alcohols. Cyclic and non cyclic C₅ products, optionally,after hydrogenation, are useful as octane enhancers and transportationfuel blend components.

EXAMPLES

The following examples illustrate the present invention. Numerousmodifications and variations are possible and it is to be understoodthat within the scope of the appended claims, the invention may bepracticed otherwise than as specifically described herein.

X-Ray Diffraction Patterns

The X-ray diffraction data (powder XRD or XRD) were collected with aBruker D4 Endeavor diffraction system with a VANTEC multichanneldetector using copper K-alpha radiation. The diffraction data wererecorded by scanning mode with 0.018 degrees two-theta, where theta isthe Bragg angle, and using an effective counting time of about 30seconds for each step.

Comparative Example—Pt/Sn-ZSM-5

Experiments were conducted on the conversion of n-pentane overPt/Sn-ZSM-5 catalyst compositions and selectivity/yield of cyclic C₅,C₁, and C₂₋₄ cracking products, at 451° C. (average values over 1 hourat each temperature) for a catalyst composition of 0.5 g ZSM-5(747:1SiO₂:Al₂O₃)/2.0 wt % Sn/0.9 wt % Pt, at conditions of 6.9 psia (48kPa-a) for n-pentane (C₅H₂), 1:1 molar H₂:C₅, 2.4 WHSV, 50 psia total(345 kPa-a). Data is shown for performance of the catalyst fresh andafter a 5 hour treatment in H₂ at 650° C. In Table 1A, the selectivitiesand yields are expressed on a molar percentage basis for the respectivecyclic C₅, CPD, C₁, and C₂₋₄ of hydrocarbons formed; i.e., the molarselectivity is the moles of the respective cyclic C₅, CPD, C₁, and C₂₋₄formed divided by total moles of pentane converted. In Table 1B, theselectivities and yields are expressed on a carbon percentage basis forthe respective cyclic C₅, CPD, C₁, and C₂₋₄ of hydrocarbons formed;i.e., the carbon selectivity is the moles carbon in the respectivecyclic C₅, CPD, C₁, and C₂₋₄ formed divided by total moles of carbon inthe pentane converted.

As can be seen, Table 1A and Table 1B show moderate, 36%, conversion ofn-pentane with 23% molar selectivity to cyclic C₅ species on a freshcatalyst composition. The selectivity to cyclic products greatly reducedafter H₂ treatment at 650° C., demonstrating undesired catalyst aging.

TABLE 1A Conversion Selectivity Yield Temperature (%) (mol %) (mol %) (°C.) C₅H₁₂ cC₅ C₁ C₂₋₄ cC₅ C₁ C₂₋₄ 451 36 23 1.5 12 8.5 0.5 4.4 452, PostH₂ 30 7.7 0.4 7.2 2.3 0.1 2.1

TABLE 1B Conversion Selectivity Yield Temperature (%) (C %) (C %) (° C.)C₅H₁₂ cC₅ C₁ C₂₋₄ cC₅ C₁ C₂₋₄ 451 36 25.3 0.3 7.5 9.2 0.1 2.7 452, PostH₂ 30 7.6 0.1 4.0 2.2 0.0 1.2

Example 1—Ferrosilicate MFI Framework Catalyst Composition Synthesis

A synthesis mixture with ˜22% solids was prepared from 940 g ofdeionized (DI) water, 53.5 g of 50% NaOH solution, 7.5 g of 97% IronSulfate Hydrate solution, 76.8 g of n-propyl amine 100% solution, 10 gof ZSM-5 seed crystals, and 336 g of Ultrasil PM™ Modified silica(containing a low level of Al) were mixed in a 2-liter container andthen charged into a 2-liter autoclave after mixing. The synthesismixture had the following molar composition:

SiO₂/Al₂O₃ ~1,180    H₂O/SiO₂ ~10.8  OH/SiO₂ ~0.13 Na/SiO₂ ~0.13 n-PA/Si ~0.25.

The synthesis mixture was mixed and reacted at 230° F. (110° C.) at 250rpm for 72 hours. The resulting product was filtered and washed with DIwater and then dried in the oven at ˜250° F. (121° C.) overnight. TheXRD pattern of the as-synthesized material showed the typical pure phaseof ZSM-5 topology is shown in FIG. 1. The SEM shown in FIG. 2 is of theas-synthesized material, and it shows that the material was composed ofa mixture of large crystals with a size of 1-2 microns. The resultingferrosilicate MFI framework ([Fe]-ZSM-5) crystals had an iron content of0.465 wt %, (Si/Fe molar ratio of 171), a SiO₂/Al₂O₃ molar ratio of˜1,120, and a sodium content of 0.5 wt % (Na/Al molar ratio of 7.3).

The as-synthesized [Fe]-ZSM-5 was calcined for 6 hours in nitrogen at900° F. (482° C.). After cooling, the sample was re-heated to 900° F.(482° C.) in nitrogen and held for three hours. The atmosphere was thengradually changed to 1.1, 2.1, 4.2, and 8.4% oxygen in four stepwiseincrements. Each step was held for 30 minutes. The temperature wasincreased to 1000° F. (540° C.), the oxygen content was increased to16.8%, and the material was held at 1000° F. (540° C.) for 6 hours.After cooling, 0.1 wt % Pt was added via incipient wetness impregnationusing an aqueous solution of tetraamine platinum hydroxide. The catalystcomposition was dried in air at room temperature for 2 hours, then at250° F. (121° C.) for 3 hours, and lastly calcined in air at 660° F.(349° C.) for 3 hours. The catalyst composition powder was pressed (15ton), crushed, and sieved to obtain 20-40 mesh particle size.

Example 2—Catalyst Composition Performance Evaluation

The above material of Example 1 was evaluated for performance. Thecatalyst composition (0.5 g) was physically mixed with quartz (1.5 g,60-80 mesh) and loaded into a reactor. The catalyst composition wasdried for 1 hour under He (100 mL/min, 30 psig (207 kPa), 250° C.) thenreduced for 1 hour under H₂ (200 mL/min, 30 psig (207 kPa), 500° C.).The catalyst composition was then tested for performance with feed ofn-pentane, H₂, and balance He, typically at 550-600° C., 5.0 psia (35kPa-a) C₅H₁₂, 1.0 molar H₂:C₅H₁₂, 14.7 WHSV, and 30 psig (207 kPa)total. Catalyst composition stability and regenerability was tested postinitial tests at 550 to 600° C. by treatment with Hz (200 mL/min, 30psig (207 kPa), 650° C.) for 5 hours, then re-testing performance at600° C.

Cyclopentadiene and three equivalents of hydrogen are produced bydehydrogenation and cyclization of n-pentane (Equation 1). This isachieved by flowing n-pentane over a solid-state, Pt containing catalystcomposition at elevated temperature. The performance ofZSM-5(414:1)/0.5% Pt of Example 1 was evaluated based on n-pentaneconversion, cyclic C₅ production (cC₅), cracking yields, and stability.These results are summarized in Table 2A, Table 2B, FIG. 3A, and FIG.3B.

$\begin{matrix}{{C_{5}{H_{12}\overset{\Delta}{\longrightarrow}C_{5}}H_{6}} + {3\; H_{2}}} & {{Equation}\mspace{14mu}(1)}\end{matrix}$

TABLE 2A Conversion (%) Selectivity (mol %) Yield (mol %) Temperature (°C.) C₅H₁₂ cC₅ CPD C₁ C₂₋₄ cC₅ CPD C₁ C₂₋₄ cC₅:C₁₋₄ 545 46 29 21 2.7 4.913 10 1.3 2.3 3.7 570 47 31 26 3.1 5.9 15 12 1.5 2.8 3.5 595 42 32 294.0 8.8 13 12 1.7 3.7 2.5 595, Post H₂ 30 32 29 4.0 10 10 8.8 1.2 3.12.3

TABLE 2B Conversion (%) Selectivity (C %) Yield (C %) Temperature (° C.)C₅H₁₂ cC₅ CPD C₁ C₂₋₄ cC₅ CPD C₁ C₂₋₄ cC₅:C₁₋₄ 545 46 30 22 0.6 3.2 1410 0.3 1.5 7.9 570 46 33 27 0.6 3.7 15 12 0.3 1.7 7.5 595 42 34 30 0.95.5 14 13 0.4 2.3 5.4 595, Post H₂ 30 35 31 0.9 6.3 11 9.5 0.3 1.9 4.9

Table 2A and Table 2B show the conversion of n-pentane and selectivityand yield of cyclic C₅, CPD, C₁, and C₂₋₄ cracking products at varyingtemperatures (average values over 8 hours at each temperature) for acatalyst composition of 0.5 g [Fe] ZSM-5(Si:Al₂ molar ratio 1100:1)/0.1wt % Pt at conditions of 5.0 psia (35 kPa-a) C₅H₁₂, 1:1 molar H₂:C₅,14.7 WHSV, 45 psia (310 kPa-a) total. In Table 2A, the selectivities andyields are expressed on a molar percentage basis for the respectivecyclic C₅, CPD, C₁, and C₂₋₄ of hydrocarbons formed; i.e., the molarselectivity is the moles of the respective cyclic C₅, CPD, C₁, and C₂₋₄formed divided by total moles of pentane converted. In Table 2B, theselectivities and yields are expressed on a carbon percentage basis forthe respective cyclic C₅, CPD, C₁, and C₂₋₄ of hydrocarbons formed;i.e., the carbon selectivity is the moles carbon in the respectivecyclic C₅, CPD, C₁, and C₂₋₄ formed divided by total moles of carbon inthe pentane converted.

As can be seen, Table 2A and Table 2B show greater than 40% conversionof pentane, at high WHSV, and 30% selectivity to cyclic C₅ species at600° C. While not the specific end product, cyclopentane andcyclopentene can be recycled to produce CPD or recovered for use inother applications. [Fe]-ZSM-5(1100:1)/0.1% Pt also produces C₁ and C₂₋₄cracking products. These are lower value, undesired side products thatcannot be recycled in this process, but can be separated and used asfeedstock for other processes or as fuels. Yield to cracking products isless than 5% while the ratio of C₅ cyclic products to cracking productsis greater than 2 at each condition tested.

In the Comparative Example, a catalyst composition of Pt/Sn-ZSM-5exhibited a 36% conversion of n-pentane with 23% selectivity to cyclicC₅ species on a fresh catalyst composition, with a selectivity to cyclicproducts greatly reduced after H₂ treatment at 650° C., demonstratingundesired catalyst composition aging, as noted above.

FIGS. 3A and 3B show cyclic C₅ yield at varying temperatures, before andafter H₂ treatment for 0.5 g [Fe] ZSM-5(400:1)/0.5% Pt at conditions of5.0 psia (35 kPa-a) C₅H₁₂, 1:1 molar H₂:C₅, 14.7 WHSV, 45 psia total(310 kPa-a). FIG. 3 shows this activity decreases over 8 hours at eachtemperature but increases after 5 hours of H₂ treatment at 650° C., thencontinues to decrease at longer time-on-stream. This performance isgreatly superior to other dehydrogenation catalysts, such as aluminasand aluminates.

Certain embodiments and features have been described using a set ofnumerical upper limits and a set of numerical lower limits. It should beappreciated that ranges from any lower limit to any upper limit arecontemplated unless otherwise indicated. Certain lower limits, upperlimits and ranges appear in one or more claims below. All numericalvalues take into account experimental error and variations that would beexpected by a person having ordinary skill in the art.

All documents described herein are incorporated by reference herein,including any priority documents and/or testing procedures to the extentthey are not inconsistent with this text. As is apparent from theforegoing general description and the specific embodiments, while formsof the invention have been illustrated and described, variousmodifications can be made without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the invention belimited thereby. Likewise, the term “comprising” is consideredsynonymous with the term “including.” Likewise, whenever a composition,a process, a method of making, or an element or a group of elements ispreceded with the transitional phrase “comprising,” it is understoodthat we also contemplate the same composition, a process, a method ofmaking, or an element or a group of elements with transitional phrases“consisting essentially of,” “consisting of”, “selected from the groupof consisting of,” or “is” preceding the recitation of said composition,a process, a method of making, or an element or a group of elements, andvice versa.

What is claimed is:
 1. A process for conversion of an acyclic C₅feedstock to a product comprising cyclic C₅ compounds includingcyclopentadiene, said process comprising the steps of contacting saidfeedstock and, optionally, hydrogen under acyclic C₅ conversionconditions in the presence of a catalyst composition to form saidproduct, wherein said catalyst composition comprises a microporouscrystalline ferrosilicate, a Group 10 metal, and, optionally, a Group 11metal, in combination with an optional Group 1 alkali metal and/or anoptional Group 2 alkaline earth metal.
 2. A process for conversion of anacyclic C₅ feedstock to a product comprising cyclic C₅ compounds, saidprocess comprising the steps of contacting said feedstock and,optionally, hydrogen under acyclic C₅ conversion conditions in thepresence of a catalyst composition to form said product, wherein saidcatalyst composition is made by the method comprising the steps of: (a)providing a microporous crystalline ferrosilicate comprising a Group 1alkali metal and/or a Group 2 alkaline earth metal; (b) heating saidmicroporous crystalline ferrosilicate in one or more steps to a firsttemperature of 450° C. or above in an atmosphere which comprises aninert gas; (c) adding oxygen to said atmosphere until the oxygenconcentration in said atmosphere is up to 20% and then cooling saidmicroporous crystalline ferrosilicate; and (d) contacting said cooledmicroporous crystalline ferrosilicate of step (c) with a source of aGroup 10 metal, and, optionally, a Group 11 metal, to form said catalystcomposition, whereby said catalyst composition having said Group 10metal and/or said Group 11 metal deposited thereon.
 3. The process ofclaim 1, wherein said catalyst composition has a Group 10 metal contentin the range from 0.005 wt % to 10 wt %, based on the weight of thecatalyst composition.
 4. The process of claim 1, wherein said Group 10metal is platinum, and said Group 11 metal is copper or silver.
 5. Theprocess of claim 2, wherein said Group 10 metal is platinum and saidsource of platinum is selected from the group consisting of platinumnitrate, chloroplatinic acid, platinous chloride, platinum aminecompounds, platinum acetylacetonate, tetraamine platinum hydroxide, andmixtures of two or more thereof, and/or said optional Group 11 metal iscopper and said source of copper is selected from the group consistingof copper nitrate, copper nitrite, copper acetate, copper hydroxide,copper acetylacetonate, copper carbonate, copper lactate, coppersulfate, copper phosphate, copper chloride, and mixtures of two or morethereof, and/or said Group 11 metal is silver, and/or said source ofsilver is selected from the group consisting of silver nitrate, silvernitrite, silver acetate, silver hydroxide, silver acetylacetonate,silver carbonate, silver lactate, silver sulfate, silver phosphate, andmixtures of two or more thereof.
 6. The process of claim 1, wherein saidGroup 1 alkali metal and/or said Group 2 alkaline earth metal is presentas an oxide.
 7. The process of claim 1, wherein said Group 1 alkalimetal is selected from the group consisting of lithium, sodium,potassium, rubidium, cesium, and mixtures of two or more thereof, and/orsaid Group 2 alkaline earth metal is selected from the group consistingof beryllium, magnesium, calcium, strontium, barium, and mixtures of twoor more thereof.
 8. The process of claim 1, wherein said microporouscrystalline ferrosilicate has a constraint index of less than
 12. 9. Theprocess of claim 1, wherein said microporous crystalline ferrosilicatehas a framework type selected from the group consisting of MWW, MFI,LTL, MOR, BEA, TON, MTW, MTT, FER, MRE, MFS, MEL, DDR, EUO, FAU, andmixtures of two or more thereof.
 10. The process of claim 1, whereinsaid microporous crystalline ferrosilicate has a Si/Fe molar ratio inthe range from 50 to
 1200. 11. The process of claim 1, wherein saidcatalyst composition has an Alpha Value (as measured prior to theaddition of said Group 10 metal, and/or prior to the addition of saidoptional Group 11 metal) of less than
 25. 12. The process of claim 1,wherein the molar ratio of said Group 1 alkali metal to Al plus Fe is atleast 0.1, and/or the molar ratio of said Group 2 alkaline earth metalto Al plus Fe is at least 0.1.
 13. The process of claim 1, wherein saidcatalyst composition provides a conversion of at least about 40% of ann-pentane feedstock with equimolar H₂ under acyclic C₅ conversionconditions of a temperature in the range of 550° C. to 600° C., ann-pentane partial pressure between 3 psia and 30 psia at the reactorinlet (21 to 207 kPa-a), and an n-pentane weight hourly space velocitybetween 5 and 20 hr⁻¹.
 14. The process of claim 1, wherein said catalystcomposition provides a carbon selectivity to cyclopentadiene of at least30% of an n-pentane feedstock with equimolar H₂ under acyclic C₅conversion conditions of a temperature in the range of 550° C. to 600°C., an n-pentane partial pressure between 3 psia and 30 psia at thereactor inlet (21 to 207 kPa-a), and an n-pentane weight hourly spacevelocity between 5 and 20 hr⁻¹.
 15. The process of claim 1, wherein saidacyclic C₅ feedstock comprises pentane, pentene, pentadiene, or mixturesof two or more thereof.
 16. The process of claim 1, wherein said cyclicC₅ compounds comprise cyclopentane, cyclopentene, cyclopentadiene, ormixtures of two or more thereof.
 17. The process of claim 1, whereinsaid acyclic C₅ feedstock comprises at least 75 wt % n-pentane.
 18. Theprocess of claim 1, wherein said cyclic C₅ compounds comprise at least20 wt % cyclopentadiene.
 19. The process of claim 1, wherein saidacyclic C₅ conversion conditions include at least a temperature of 450°C. to 650° C., the molar ratio of said optional hydrogen co-feed to theacyclic C₅ feedstock is in the range of 0.01 to 3, said acyclic C₅feedstock has a partial pressure in the range of 3 psia to 100 psia (21to 689 kPa-a), and said acyclic C₅ feedstock has a weight hourly spacevelocity in the range from 1 hr⁻¹ to 50 hr⁻¹.